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| Daguerreotype framed in glass |
Louis Jacques Mande Daguerre invented daguerreotype photography in France in the 1830s. Henry Fox Talbot created the Calotype several years later. Daguerre discovered that he could expose an image onto a copper plate coated with iodized silver. He found that the image lasted if it was exposed to mercury vapor and a salt solution. Daguerreotypes were put on polished silver, so they were reflective. The daguerreotype is a negative image. It was framed so it wouldn't tarnish.
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| Calotype of the Colosseum |
Talbot came up with a bit of a different photographic process. He first brushed photographic paper with a salt solution and let it dry. Next he brushed it with silver nitrate and let that dry, creating a silver chloride. Then Talbot added Gallic acid to make the paper more sensitive to light. After being exposed he would fix the image with an iodized solution. Finally, to develop the photo, a negative was placed on top of photo paper, laid flat in a glass frame and exposed to sunlight. Unlike the daguerreotype, the Calotype negative allowed for an unlimited number of prints.
JBird
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